Google has an 'unofficial' weather api which supports a number of locations in each country to provide current weather conditions and a 3 day future prediction.

To view the locations supported in your country you can use the following url http://www.google.com/ig/cities?country=BE .

To get the weather info in XML format use the following syntax: http://www.google.com/ig/api?weather=Antwerpen but it seems you can also query cities which are not officially supported. I guess Google takes the closest city to you location. That way this http://www.google.com/ig/api?weather=Landen,Belgium also gives results.